I've written a simple IPhone app for timing long exposures accounting for reciprocity.
It uses a simple table format for reciprocity data that allows you to add your own films or tables you find on the net. I've include some standard b&w manufacture data along with some tables graciously provided by Don Kirby, Howard Bond and Bruce Barnbaum.
More info here.
App Store
www.davideisenlord.com/FilmTimer
Ike
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